Stiegler Amy L, Boggon Titus J
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA.
Nat Commun. 2017 Sep 11;8(1):506. doi: 10.1038/s41467-017-00483-x.
The two p190RhoGAP proteins, p190RhoGAP-A and -B, are key regulators of Rho GTPase signaling and are essential for actin cytoskeletal structure and contractility. Here we report the discovery of two evolutionarily conserved GTPase-like domains located in the 'middle domain', previously thought to be unstructured. Deletion of these domains reduces RhoGAP activity. Crystal structures, MANT-GTPγS binding, thermal denaturation, biochemical assays and sequence homology analysis all strongly support defects in nucleotide-binding activity. Analysis of p190RhoGAP proteins therefore indicates the presence of two previously unidentified domains which represent an emerging group of pseudoenzymes, the pseudoGTPases.A growing number of 'pseudoenzymes' with a regulatory role in signal transduction processes but without catalytic activity are being identified. Here, the authors identify two pseudoGTPase domains in p190RhoGAP, characterize them biochemically and structurally and show that they influence RhoGAP activity.
两种p190RhoGAP蛋白，即p190RhoGAP-A和-B，是Rho GTPase信号传导的关键调节因子，对肌动蛋白细胞骨架结构和收缩性至关重要。在此，我们报告发现在先前被认为是无结构的“中间结构域”中存在两个进化上保守的GTP酶样结构域。缺失这些结构域会降低RhoGAP活性。晶体结构、MANT-GTPγS结合、热变性、生化分析和序列同源性分析均有力支持核苷酸结合活性存在缺陷。因此，对p190RhoGAP蛋白的分析表明存在两个先前未被识别的结构域，它们代表了一个新兴的伪酶类群，即伪GTP酶。越来越多在信号转导过程中起调节作用但无催化活性的“伪酶”被发现。在此，作者在p190RhoGAP中鉴定出两个伪GTP酶结构域，对其进行生化和结构表征，并表明它们影响RhoGAP活性。
